Project Summary/Abstract: An emerging body of work shows that unhealthy alcohol use substance use, smoking, and depression often co-occur in HIV-infected patients. In a large multisite observational study of aging and HIV, unhealthy alcohol use, substance use smoking, and depression were common among those with HIV and exhibited striking temporal concordance, often remitting and recurring together. For example, greater alcohol use decreases the odds of smoking cessation. While unhealthy alcohol use, substance use, smoking, and depression often co-occur, their screening and treatment does not. Screening and treatment strategies for these conditions are typically specified separately and enacted separately because of a multitude of factors, including distinct clinical guidelines, varying strength of evidence underlying those guidelines and distinct providers and programs for the treatment of each condition. As a result, patients who are screened for one may not be screened for another, and patients who are treated for one may not be treated for another. We propose developing a decision-analytic model to evaluate beneficial effects as well as potentially harmful effects and resource implications of integrated screening and treatment.